Answer
Set $u = 4-7x$ and substitute $4-7x$ with $u$ in the integral
Work Step by Step
Setting $u = 4-7x$ would result in the integral $\int (u)^{-6} dx$, which is easier to integrate.
$u = 4-7x$
$du = -7$
$\frac{-1}{7}\int u^{-6} du = (\frac{-1}{7}) \frac{-1}{5}u^{-5} = \frac{(4-7x)^{-5}}{35} $